Fuel guage repair

How to keep the Cessna 170 flying and airworthy.

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Re: Fuel guage repair

Postby dstates » Fri Feb 28, 2020 1:50 pm

George and Gary,

You guys may be right. I haven't looked at how far the original gauge is from the top of the tank when it is at it's upper limit of travel. If the mounting tube for the gauge is truly in the middle of the tank I should be able to make it work (and possibly better than the original). I'll take my original back to the hangar this weekend and check it out and report back. I'm hoping you are right because the new gauge definitely has more up travel than the old gauge.

Doug
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Re: Fuel guage repair

Postby n2582d » Fri Feb 28, 2020 2:50 pm

Here’s a picture from Bruce.
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Re: Fuel guage repair

Postby dstates » Fri Feb 28, 2020 3:45 pm

n2582d wrote:Here’s a picture from Bruce.


Thanks, Gary.
A picture is worth a thousand words.
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Re: Fuel guage repair

Postby johneeb » Fri Feb 28, 2020 10:33 pm

Doug,
I have been using the Spruce gauges, like yours, for over 15 years and have been satisfied with there performance. Initially I did have to fiddle with them to get them to indicate properly, now they indicate approximately the same as the fuel Computer which is incredibly accurate.
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Re: Fuel guage repair

Postby gahorn » Sun Mar 01, 2020 2:32 am

Of course, according to FAA.... the gauge is serviceable as long as it reads “Empty” when the tank is. It makes no difference if it is accurate or not in any other position. (Just thought I’d remind us all that we are pickier than FAA.). :lol:
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An originality nut (mostly) for the right reasons. ;)
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Re: Fuel guage repair

Postby DaveF » Sun Mar 01, 2020 11:46 pm

Since most people haven't read CAR3, here's the relevant section. (bold added)

§ 3.672 Fuel quantity indicator . Means shall be provided to indicate to the flight personnel the quantity of
fuel in each tank during flight.
Tanks, the outlet and air spaces of which are interconnected, may be
considered as one tank and need not be provided with separate indicators. Exposed sight gauges shall be so
installed and guarded as to preclude the possibility of breakage or damage. Sight gauges which form a trap in
which water can collect and freeze shall be provided with means to permit drainage on the ground. Fuel
quantity gauges shall be calibrated to read zero during level flight when the quantity of fuel remaining in the
tank is equal to the unusable fuel supply as defined by § 3.437.
Fuel gauges need not be provided for small
auxiliary tanks which are used only to transfer fuel to other tanks, provided that the relative size of the tanks,
the rate of fuel transfer, and the instructions pertaining to the use of the tanks are adequate to guard against
overflow and to assume that the crew will receive prompt warning in case transfer is not being achieved as
intended.
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Re: Fuel guage repair

Postby dstates » Mon Mar 02, 2020 1:25 am

I was able to set up the Spruce gauge yesterday. Here are some pictures.

Here is new and old next to each other.
3D30BBF0-09BB-4016-B22A-55E4B85245A6.jpeg


Here is the new gauge showing empty.
C0E1B0C9-AA0A-4F9B-A448-17D706E37EB9.jpeg


Here is the new gauge showing full.
456B9D75-FA90-4208-B42D-4592B0A9A6D1.jpeg


Unfortunately when I went to set up the second gauge the aluminum rod broke when I bent it. I’ll be calling tomorrow to see if they will replace it.
9E8AFB00-5728-4EE4-B071-A368D16E81E0.jpeg
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Re: Fuel guage repair

Postby n2582d » Mon Mar 02, 2020 6:03 am

I was curious just how many inches of fuel are in the tank when it is at the unusable level; i.e. 2.5 gallons. The flat bottom portion of the tank measures roughly 19" X 31". Not considering the wing dihedral -- like an A model rather than a B model -- I figure there should be just short of an inch of fuel in the tank at 2.5 gallons. One of you engineers could double check my numbers. Math isn't my strong suit. :oops:
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Re: Fuel guage repair

Postby dstates » Mon Mar 02, 2020 1:08 pm

n2582d wrote:I was curious just how many inches of fuel are in the tank when it is at the unusable level; i.e. 2.5 gallons. The flat bottom portion of the tank measures roughly 19" X 31". Not considering the wing dihedral -- like an A model rather than a B model -- I figure there should be just short of an inch of fuel in the tank at 2.5 gallons. One of you engineers could double check my numbers. Math isn't my strong suit. :oops:


For a 19" x 31" container, every inch of depth would be 589 cubic inches which is equal to 2.54 gallons. I agree with your numbers... :)
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